Tule Wind Project San Diego County, California · P:\Mpls\05 CA\37\05370007 tule wind...

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Tule Wind Project San Diego County, California Desktop Study Prepared for Iberdrola Renewables November 2009

Tule Wind Project San Diego County, California Desktop Study Prepared for Iberdrola Renewables November 2009

4700 West 77th Street Minneapolis, MN 55435-4803 Phone: (952) 832-2600 Fax: (952) 832-2601

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Tule Wind Project San Diego County, California

Desktop Study

Table of Contents

Executive Summary ...................................................................................................................................... 1

1.0 Description of Proposed Development .................................................................................................. 2

2.0 Purpose and Scope ................................................................................................................................. 3

3.0 Site Geology ........................................................................................................................................... 4

4.0 Geologic/Geotechnical Risks ................................................................................................................. 6 4.1 General Summary of Geologic and Geotechnical Risks ............................................................. 6 4.2 Soil Conditions............................................................................................................................ 7 4.3 County of San Diego Guidelines ................................................................................................ 7

4.3.1 Fault Rupture ................................................................................................................. 8 4.3.2 Ground Shaking ............................................................................................................. 8 4.3.3 Liquefaction ................................................................................................................... 8 4.3.4 Landslides ...................................................................................................................... 9 4.3.5 Expansive Soils .............................................................................................................. 9 4.3.6 Flash Floods and Debris Flows ...................................................................................... 9 4.3.7 Alluvial Fan Floods ........................................................................................................ 9 4.3.8 Urbanization ................................................................................................................. 10 4.3.9 Landform Modification ................................................................................................ 10 4.3.10 Dam Failure ................................................................................................................. 10 4.3.11 Faulty Drainage Facilities ............................................................................................ 10

5.0 Feasible Foundation Types .................................................................................................................. 11

6.0 Electrical Design .................................................................................................................................. 13 6.1 Soil Electrical Resistivity .......................................................................................................... 13 6.2 Soil Thermal Resistivity ........................................................................................................... 16 6.3 Recommended Testing .............................................................................................................. 16

7.0 Civil Design ......................................................................................................................................... 17

8.0 Recommended Field Investigation ....................................................................................................... 18 8.1 Preliminary Geotechnical Site Investigation ............................................................................. 18 8.2 Final Geotechnical Site Investigation ....................................................................................... 19 8.3 Limitations ................................................................................................................................ 21

References ................................................................................................................................................... 22

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List of Figures Figure 1 Site Location Figure 2 Site Topography Figure 3 Bedrock Geology Figure 4 Soil Map Figure 5 Unified Soil Classification Figure 6 Depth to Weathered Bedrock

List of Tables Table 1 Summary of Geologic Hazards ......................................................................................... 6 Table 2 Soil Type and Assumed Electrical Resistivity ................................................................. 14 Table 3 Classification of Resistivity ............................................................................................ 15 Table 4 Estimated Scope and Cost of Future Phases .................................................................... 20

Appendix Site Seismic Information

Barr Engineering Company 1

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Executive Summary

The following is based on published and other publically available information. The costs noted

below are subject to the limitations enumerated in the report.

• The site is underlain by bedrock with potentially thin, if any, soil covering in some areas. This will not pose a hazard to the foundations, but will likely complicate, and increase the cost of, construction of roads, foundations, and buried collection and grounding systems.

• A combination of turbine foundation types may be the most economical approach. It is likely that a spread footing will be most economical at locations with soil greater than 3 ft thick, and a rock socket, rock anchor, or P&H-style will be most economical at sites with thin soil. Based on the USDA soil mapping, it appears that proposed turbine sites divide about 50 percent with thin soils and 50 percent with thick soils.

• Project area seismicity is high.

• The soils encountered across the site appear to be moderately corrosive to steel and concrete.

• Soil resistivity is likely to be >10,000 Ωcm in the dominantly silty sand soils and in areas where bedrock is shallow or at the surface.

• The anticipated the method for constructing the roads is to level and compact existing ground, areas with steep grades or high percentage of fines like dry stream crossings a layer of 4 to 6 inches of gravel would be desirable.

• A preliminary geotechnical investigation is strongly suggested because of the uncertainty of the need and cost-effectiveness of alternative turbine foundation designs. There are no appear significant geological hazards that need to be evaluated, but this can also be confirmed at least in part via preliminary investigation. The first phase of investigation would consist of reconnaissance and test pitting to evaluate soil thicknesses. This will cost on the order of $18,000 - $23,000. If indicated by the first phase, the second phase of preliminary investigation would consist of limited drilling to allow better comparison of alternative foundation types. This will cost on the order of $51,000 - $64,000.

• Following are the preliminary estimates of final investigation, turbine foundation engineering and construction costs. Table 4 contains additional detail.

o Use of a single spread footing design throughout the project will incur the cost of the foundation design and about $3,700 per turbine in geotechnical investigation and engineering. The foundation size likely will be smaller than typical due to strong site subgrade. Construction costs may be higher than normal due to creating a level surface after excavation, the need to manufacture onsite backfill or transport significant amounts of fill to about half the turbine locations.

o Use of a spread footing design and a rock anchor/socket design will incur the cost of two foundation designs, about $3,700 per turbine in geotechnical investigation at the spread footing sites and $4,600 to $8,500 per turbine in geotechnical investigation at the rock anchor/socket sites. The rock anchor option will require additional anchor testing at 2-5% of the anchors, costing about $20,000 per test. Construction costs would be typical for the spread footings and are assumed to be lower than a typical spread footing at the other sites where rock anchor/socket foundations are used. P&H would need to be contacted for the cost of a P&H style foundation design.



1.0 Description of Proposed Development

1. The proposed Tule Wind Project is located near Live Oak Springs in San Diego County,

California (Figure 1).

2. The wind project is planned to consist of 66 wind turbines. Figures 2 and 3 are maps of the

proposed layout. The proposed wind turbine is a Gamesa G87 2.0 MW.

3. In November 2007 Barr completed site reconnaissance in order to evaluate road construction.

The results of that work are summarized in this desk top study.



2.0 Purpose and Scope

The scope of the work is limited to review and assessment of readily available existing information.

The goals of this report are to:

• Review readily available existing information, such as geologic maps and reports, geophysical reports, topographic maps, wetlands maps, flood maps, proposed development maps/turbine layouts, and aerial photographs.

• Summarize geologic/geotechnical conditions.

• Identify and qualify geologic/geotechnical risks.

• Recommend a geotechnical investigation approach.

• Summarize soil conditions as it relates to electrical design parameters.

• Recommend whether or not a preliminary field investigation is warranted, and if so, recommend a scope.

• Identify appropriate foundation types and issues.

• Identify potential roadway issues.

• Provide conceptual-design level cost estimates.



3.0 Site Geology

This information is based largely on the El Cahon 30’ x 60’ Quadrangle geologic map and report

(Todd, 2004) issued by the USGS.

The project site is in the Peninsular Ranges physiographic province. In this area, volcanic and

marine sedimentary rocks ranging in age from Paleozoic to Mesozoic were intruded by granitic rocks

in late Mesozoic to Cenozoic time. There were many granite intrusions, to the extent that the

aggregate is classified as what is known as a batholith. These intrusions distorted and

metamorphosed the earlier sedimentary rocks, and later intrusions deformed earlier intrusions. The

intrusions and deformation were driven by the subduction to the west, where oceanic crust was thrust

under the North American plate. Eventually, this subduction ended, and the relative motion of the

Pacific plate and the North American plate transitioned into the San Andreas fault zone, which is

several miles east of the site. This introduced new stress and deformation to the region. As a result

of the intrusions and deformation, many of the rocks at the site have undergone metamorphism and

exhibit internal fabrics and foliations.

Based on the USGS on-line gis data base, three geologic units underlie the site: gr-m and sch under

the western ¼ and grMz under the eastern ¾ of the project area (Figure 3). Note that the descriptions

and notations vary between the published version of the El Cajon quadrangle and the USGS on-line

gis data base. The quadrangle shows more detail and more units than the on-line database. The

following descriptions are taken from the quadrangle, and the approximate equivalencies to the on-

line units shown on Figure 3 are noted:

grMz approximates Klp on the quadrangle. Klp is Tonalite of La Posta (Early and Late

Cretaceous)—Hornblende-biotite trondhjemite in western part, and biotite trondhjemite and

granodiorite in eastern part. Unit is leucocratic, homogeneous, largely undeformed, and

inclusion-free, but locally, pluton margins are moderately to strongly foliated. Color index from 6

to 15.

grm approximates Kgm on the quadrangle. Kgm is Tonalite of Granite Mountain (Early

Cretaceous)—Biotite-hornblende tonalite; hornblende-biotite tonalite, lesser granodiorite; and

minor quartz diorite. Medium- to coarse-grained; weak to very strong foliation. Color index from

17 to 27.



Sch approximates JTrm on the quadrangle. JTrm is Metasedimentary and metavolcanic rocks

(Jurassic and Triassic)—Interlayered semi-pelitic, pelitic, and quartzitic schists; calcsilicate-

bearing feldspathic metaquartzite; and minor small-pebble metaconglomerate. Includes layers of

sandstone, quartz-pebble conglomerate, mudstone, and amphibolite. Interpreted to be

metamorphosed submarine fan deposits and intercalated volcanic rocks; equivalent to the Julian

Schist of Hudson (1922)

Based on these descriptions, some of the rocks may be massive and relatively structureless and some

may have internal structure and foliation. Much of the rock may be very strong and shallow to the

point that excavation may be difficult and require blasting. As such, foundation types such as the

rock socket and the rock anchor can be considered. One issue in evaluating these foundations will be

anisotropy in the rock. Because of internal fabric, some rocks may have anisotropic strength

characteristics. These anisotropies will also need to be considered and evaluated along cut slopes.

Each proposed turbine location will need to be evaluated because of the variations in the bedrock

across the site.

Figure 4 shows the mapped soil types. Figure 5 shows the USCS soil classifications. The vast

majority of the area is underlain by silty sand (SM). Figure 6 shows the approximate thickness of the

site soils. Soils across much of the project area are thin, less than 1 meter, indicating that excavation

for foundations and collection systems and roads may be difficult.

Given the thin and well-drained soils, crystalline bedrock, and high and steep relief, groundwater

should not be an issue at the site. This is supported by the soil mapping which generally indicates

the water table is greater than 80-inches deep.



4.0 Geologic/Geotechnical Risks

4.1 General Summary of Geologic and Geotechnical Risks Table 1 is a summary of geologic and geotechnical hazards for the site.

Table 1 Summary of Geologic Hazards

Hazard Present at Site? Comment

Flooding/High groundwater No The proposed turbine sites are on high ground between drainages, and soils are generally well drained.

Landslides Possibly in some areas

The site has high relief and generally thin and granular soils. Many of the bedrock units contain internal foliations and so have plains of weakness. These will need to be considered when designing cut slopes.

Subsidence – Pumping No

Project site is underlain by bedrock with a framework capable of resisting subsidence due to production of oil, gas or water. There are no known oil or gas fields and no large volume extraction of water.

Subsidence – Mining No There is no mining activity in the area. Subsidence – Caves/Karst No The bedrock is not susceptible to dissolution. Earthquake/Seismicity Yes The site is in a high seismicity area. Earthquake/ground rupture No There are no mapped faults in the project area.

Liquefaction Unlikely Seismicity is high and soils are sandy. However, soils tend to be thin and rocky with a relatively low regional water table.

Swelling/shrinking soil No High shrink/swell soils are not present.

Corrosive soil Possibly The soil survey reports generally moderate concrete corrosion and moderate steel corrosion.

Made ground Unlikely There is very low potential for filled areas associated with rural living practices.

Collapsible soil No There are no collapsible deposits at the site. Volcanic activity No No current volcanic activity exists in the region.

Quick clay No Quick clay conditions are not known or likely to be present.

While not necessarily a geologic hazard, parts of the area may have shallow bedrock which could

complicate excavations for foundations, collection system cables, and roads.



4.2 Soil Conditions The project site has surficial soils of colluvial and alluvial origin, consisting primarily of sand and

gravel. The fairly dry conditions coupled with generally well drained soil conditions should provide

for a favorable construction environment. However, low areas and drainage swales should be

avoided or mitigated when laying out proposed access roads and turbine locations. In addition,

shallow bedrock is present at the project site, which may complicate excavations for foundations,

collection system cables, and roads.

4.3 County of San Diego Guidelines The County of San Diego provides Guidelines for Determining Significance of various issues

(http://www.sdcounty.ca.gov/dplu/procguid.html#guide). The geologic hazards focus on the

following issues:

• Fault rupture

• Ground shaking

• Liquefaction

• Landslides

• Expansive soils

The hydrology hazards focus on the following issues:

• Flash floods and debris flows

• Alluvial fan floods

• Urbanization

• Landform modification

• dam failure

• Faulty drainage facilities

The County also lists tsunamis and seiches as possible issues in both the geologic and hydrologic

hazards, but as the site is far inland and not adjacent to any large water bodies, these are not risks.



4.3.1 Fault Rupture The information on mapped faults presented by the County and the USGS and CGS on-line databases

indicates that there are no mapped faults in the development area. The closest mapped fault is just

southeast of proposed turbine Q2. All of the mapped faults in the area of the project site are likely

Quaternary in age. There are no adjacent historic, Holocene, or Late Quaternary faults, indicating

that the faults have not experienced rupture in the last 100,000 years. The Elsinor Fault zone is

approximately 5 miles to the northeast.

Most of the proposed project structures (turbines, substation, met tower) are not designed for human

occupancy. Only the O&M building is designed for human occupancy. None of the proposed

turbine locations are within 50 ft of the trace of an Alquist-Priolo fault or a County special study

fault. Therefore, fault rupture does not appear to be a significant risk to the project.

4.3.2 Ground Shaking All of San Diego County is located within Seismic Zone 4, which is the highest seismic zone and is

subject to ground shaking. Appendix A contains seismic design parameters derived from the USGS

earthquake hazards program accessed November 11, 2009

(http://earthquake.usgs.gov/hazards/products/conterminous/2008/software/).

Load factoring for wind turbines allows for the use of the greater of the wind load or the seismic

load. Invariably, the wind load is greater, and so the seismic loading is not a factor for wind

turbines. However, ground shaking will need to be evaluated as part of the design of other project

structures.

4.3.3 Liquefaction Liquefaction is a potential risk where loose, saturated sandy soils may be subjected to seismic

energy. The County has identified specific soil units that are susceptible to liquefaction risk,

including the Mottsville loamy coarse sand (MxA) 0-2 percent slopes. The site contains a Mottsville

soil unit (MvC) that is a loamy coarse sand, 2 to 9 percent slopes, with depth to water table more than

80 inches (http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx). This is a well-drained soil.

It does not appear that any of the currently proposed turbine locations are on the Mottsville soil, but

proposed site C4 is close to an area of Mottsville soil. It should be noted that this general description

– loamy coarse sand with depth to water table more than 80 inches, applies to virtually all of the site

soil types. However, many of the other soil types are less than 80 inches thick over rock and

weathered rock.



In summary, the site contains a soil type that is close to but does not exactly match the County’s

descriptor of potential risk areas. Many of the site soils have similar general descriptions. However,

the soils do not appear to be saturated, so overall the risk of liquefaction appears to be low. Still, this

should be further evaluated as the project moves forward and site-specific information is generated,

including the locations of other project structures like met towers, O&M building, substation, and

collection system.

4.3.4 Landslides The project site has areas of steep slopes, greater than 25%. Some bedrock units have foliation and

other plains of weakness that could contribute to instability. There are areas mapped as talus

deposits indicating past mass wasting. The project development will include cut slopes and grading

that could affect slope stability. Therefore, this is an issue that will need to be further addressed as

the project moves forward.

4.3.5 Expansive Soils Certain types of clayey soils (“fat” clays) have a tendency to absorb water and swell and then shrink

as they dry. This can exert considerable pressure on structures, leading to cosmetic and structural

damage. The County has identified specific soil units that are susceptible to expansion (shrink-swell)

risks. None of these specifically named soils are present at the site. In addition, the site soils are

silty sands (SM), not fat clays (CH or MH) (Figure 5). Therefore, the risk of expansive soils is not

significant.

4.3.6 Flash Floods and Debris Flows Debris flows, also known as mudflows, are shallow water-saturated landslides that travel rapidly

down slopes carrying rocks, brush, and other debris. The path of a mudflow is determined by local

topography, and will typically follow existing drainage patterns. Project facilities will be constructed

on high ground and are not expected to be susceptible to debris flows or flash floods.

4.3.7 Alluvial Fan Floods Alluvial fans are a desert phenomenon where streams emerge from canyons and deposit sand and

rock in a cone-shaped formation fanning out from the canyon mouth. Alluvial fans form in arid and

semi-arid environments where steep mountain fronts meet flatter valley floors. The infrequent but

intense storms in these environments produce flash floods that can carry heavy debris and sediment

loads. No alluvial fans have been identified on the project site.



4.3.8 Urbanization The conversion of undeveloped, natural areas to urbanized uses throughout San Diego’s watersheds

can contribute to increased potential for flooding, by increasing the rate and amount of runoff in a

watershed and altering drainage patterns. The proposed wind farm will result in a negligible change

to the impervious area.

4.3.9 Landform Modification Any alteration to natural drainage patterns by modifying landforms that control the conveyance of

surface water can increase the potential for flooding. The proposed wind farm will not alter the

drainage patterns.

4.3.10 Dam Failure Dam failure inundation is flooding caused by the release of impounded water from failure or

overtopping of a dam. The failure of a dam occurs most commonly as a result poor design, neglect,

or structural damage caused by earthquakes. There are no dams identified in the project area.

4.3.11 Faulty Drainage Facilities Drainage facilities including storm drains, culverts, inlets, channels or other such structures are

designed to prevent flooding by collecting stormwater runoff and directing flows to either the natural

drainage course and/or away from urban development. The capacity of a drainage structure can

typically be adequately determined by a hydrology and drainage study; however if drainage facilities

are not adequately designed or built, or properly maintained, the facilities can overflow or fail,

resulting in flooding.

The drainage facilities in the project site are limited to small culverts on intermittent streams.



5.0 Feasible Foundation Types

Feasible foundation types for the Tule Wind Project are in part selected based upon a combination of

critical geotechnical, climatological, and mechanical factors which drive the design selected.

1. Geotechnical Factors. The project site geology consists of shallow bedrock overlain by

mostly sand and gravel. The site has high seismicity but is of a magnitude that would not

supercede design loads due to wind (IBC, 2006). The water table is likely to be relatively

deep across most of the project area.

2. Climatological Factors. As stated in Section 4.2, flooding will be of short duration.

3. Mechanical Factors. The proposed turbine for the project is the Gamesa G87.

The following foundation types are not feasible or are not recommended based on the combination of

critical geotechnical, climatological, and mechanical factors identified:

1. Deep Foundations. Due to the predicted competency of the soil deposits, deep foundations

will likely not be required. Less expensive foundation options are suitable for the site.

2. Stone Columns Supporting Spread Footing. Soils and rock at the project site likely do not

need this type of soil improvement technique.

The following foundation types are feasible based on the combination of critical geotechnical,

climatological, and mechanical factors identified:

1. Spread Footing. The soil deposits and bedrock are typically suitable for support of a spread

footing. A level foundation subgrade is difficult to achieve in bedrock, and the use of lean

concrete and engineered fill is often needed to level the bedrock subgrade.

2. Rock Socket Foundation. At sites where bedrock is encountered at very shallow depths,

i.e,. within 1-3 feet of the ground surface, a rock socket foundation may be appropriate. This

foundation type may be feasible at some locations. This type of foundation is constructed by

blasting an excavation approximately 20’x20’x20’ into the bedrock, placing an anchor bolt

cage and reinforcing in the excavation, and filling the excavation with concrete. The success

of this foundation type is highly dependent on the rock strength, rock conditions and blasting



techniques. Each site needs to be evaluated accordingly. There is more uncertainty

associated with a rock socket foundation than with a conventional spread footing.

3. Rock Anchor Foundation. At sites where strong, massive bedrock is encountered at very

shallow depths, i.e. within 1-3 feet of the ground surface, a rock anchor foundation may be

appropriate. This foundation type may be feasible at some locations. This type of foundation

is constructed by blasting an excavation approximately 25’-35’ in diameter by 7’-9’ into the

bedrock, drilling anchors to an approximate depth of 20’-50’, placing an anchor bolt cage and

reinforcing in the excavation, and pouring a concrete cap. This type of foundation is also

dependent on the rock strength and condition. There is also more uncertainty associated with

a rock anchor foundation than with a conventional spread footing.

4. Patrick and Henderson Style Foundation. P&H style caissons have been constructed in

similar soil and rock conditions found at the project site. The P&H style foundation is known

to occasionally have issues with foundation movement and stiffness, but is feasible to

construct at this project.

Based on the site characteristics discussed in this report, it is likely that all of these foundation types

may be cost competitive. The site is underlain by bedrock with potentially thin, if any, soil covering

in some areas. This will not pose a hazard to the foundations, but will likely increase the cost of the

foundation construction. Rock removal may be required for turbine locations with shallow bedrock

in order to achieve a typical 7 foot embedment for a spread footing foundation. An alternative to

using a spread footing foundation at turbine locations with shallow bedrock (<3 feet of soil) is to use

a rock socket, rock anchor or P&H style foundation. This would require a more intensive

geotechnical investigation and foundation engineering effort. These foundation types may reduce

costs due to reduced quantities of steel and concrete, but these savings are offset to some degree by

the cost of blasting or installing rock anchors. Alternatively, a spread footing may work at all

proposed locations, but the costs of excavation, supplemental lean concrete with engineered fill

needed to level the bedrock, and crushing rock for backfill or importing backfill over the foundation

will add to the costs of construction. Barr recommends preparing detailed designs based on site-

specific conditions to better estimate the cost of constructing these foundations. It may be useful to

include a contractor in preparing the cost estimate, as they tend to have a better understanding of the

difficulties associated with blasting and other construction issues. A spread footing would be most

feasible in locations with soil thicknesses greater than 3 feet, which based on the soil mapping is

about 50 percent of the proposed turbine locations.



6.0 Electrical Design

6.1 Soil Electrical Resistivity The soil, bedrock, and groundwater conditions of the site indicate generally high resistivity

subsurface conditions throughout the project site located in San Diego County, California. Based on

a summary of the soil properties from the USDA NRCS-NCGC SSURGO Soil Database of about

2,200 acres within a 500-feet radius of each proposed structure, the general soil types relevant to the

Tule Wind Project are the La Posta, Sheephead, Tollhouse, Kitchen Creek, and Holland, all of which

consist of silty sand. These soils have relatively low clay contents, from 7.5 to 11.5 percent.

Bedrock is present near the surface across the entire project site. Resistivity will likely be higher

where soil cover is thin or not present. The site has thin and well-drained soils, crystalline bedrock,

and high and steep relief, thus groundwater should not affect resistivity.

For most engineering applications in soils, the motion of ions in the interstitial formation water is the

dominant factor affecting the electrical resistivity. Ions in the formation water come from the

dissociation of salts such as sodium chloride, magnesium chloride, etc. (Mooney, 1980). For water-

bearing earth materials, the resistivity decreases with increasing:

1. Fractional volume of the material occupied by water

2. Salinity or free-ion content of the water

3. Interconnection of the pore spaces (permeability)

4. Temperature

The presence of clay minerals tends to decrease the resistivity because: (a) the clay minerals can

combine with water, (b) the clay minerals can adsorb cations in an exchangeable state on the surface,

and (c) the clay minerals tend to ionize and contribute to the supply of free ions.

The general range of electrical resistivities for alluvium and sands is from 1,000 to 80,00 ohm-

centimeters (Ωcm) or 10 to 800 ohm-meters (Ωm). Values can range from 100 to 10,000 Ωcm (1 to

100 Ωm) for clays. The general range of electrical resistivities for schist, gneiss, and granite are

from 2,000 to 1E6 Ωcm (20 to 1E4 Ωm), 6.8E6 to 3E8 Ωcm (6.8E4 to 3E6 Ωm), and 4.5E5 to

1.3E8 Ωcm (4.5E3 to 1.3E6 Ωm), respectively (Telford, 1976).

The predominant factor affecting the electrical resistivity of the soil throughout the Tule Wind

Project area appears to be the presence of thin, silty sand soils overlying shallow igneous (granite)



and metamorphic (schist and gneiss) bedrock. The soil survey from San Diego County, California,

indicates the soils consist of mostly silty sand, and thus are likely to have soil resistivities

>10,000 Ωcm. Shallow bedrock will likely have resistivity >10,000 Ωcm.

Climatic variables, including fluctuating average low and high air temperatures of 28°F to 84°F, are

important to note when comparing shallow soil electrical resistivity values to studies from other

climates (IEEE, 1983). The electrical resistivity of surficial soils will decrease when the soils are

warm, increase when cold, and will be notably higher when soils are frozen. However, the bulk

resistivity of soils through the depth of construction is not likely to be impacted by air temperature

fluctuations. High soil moisture will decrease resistivity.

Table 2 shows the soil types listed in the USDA NRCS-NCGC SSURGO database with resistivity

categories assumed on the basis of soil characteristics and clay content provided for each soil type.

Table 2 Soil Type and Assumed Electrical Resistivity

Soil Series Name Soil Symbol Taxonomic Description

USCS

Clay Content(%)

Site Coverage

(%)

Assumed Electrical

Resistivity Ωcm

La Posta LcE2 Entic haploxerolls, sandy, mixed, mesic SM 7.5 23.1 >10,000

Sheephead SpG2 Entic ultic haploxerolls, loamy, mixed, mesic SM 10.0 17.4 >10,000

La Posta LaE2 Entic haploxerolls, sandy, mixed, mesic SM 7.5 15.1 >10,000

La Posta LdG Entic haploxerolls, sandy, mixed, mesic SM 7.5 11.9 >10,000

Tollhouse ToE2 Entic haploxerolls, loamy, mixed, mesic, shallow SM 11.5 11.2 >10,000

Kitchen Creek KcD2 Ultic argixerolls, coarse-loamy, mixed, mesic SM 7.5 9.3 >10,000

Holland HnE Ultic haploxeralfs, fine-loamy, mixed, mesic SM 11.0 4.1 >10,000

La Posta LdE Entic haploxerolls, sandy, mixed, mesic SM 7.5 2.6 >10,000

Tollhouse ToG Entic haploxerolls, loamy, mixed, mesic, shallow SM 11.5 2.1 >10,000

Holland HnG Ultic haploxeralfs, fine-loamy, mixed, mesic SM 11.0 1.9 >10,000

Note: Soils comprising <1% of the project area were not included in this table.



The American Petroleum Institute (API) provides guidance for the potential corrosivity of materials

based upon resistivity measurements (API-651, Cathodic Protection of Aboveground Petroleum

Storage Tanks, 1996). Following Table 3 lists the General Classification of Resistivity (adapted

from API 651, Chapter 5.3.1.2, Table 1).

Table 3 Classification of Resistivity

Resistivity Range, Ωcm

Resistivity Range, Ωm

Resistivity Range, Ω feet Potential Corrosion Activity

<500 <5 <16 Very Corrosive

500 – 1000 5 – 10 16 – 33 Corrosive

1000 – 2000 10 – 20 33 – 66 Moderately Corrosive

2000 – 10,000 20 – 100 66 – 330 Mildly Corrosive

> 10,000 > 100 > 330 Progressively Less Corrosive

Based on this reference, the Tule Wind Project soils and bedrock appear likely to have very low

corrosivity. This is somewhat in contrast to the soil descriptions which indicate most site soils near

the proposed turbine locations are mildly corrosive to steel and concrete. More corrosive soil

conditions might be encountered where there are localized increases in clay content and increased

moisture conditions. More corrosive bedrock conditions might be encountered where there are

localized increases in weathering, fracturing, and/or moisture content.

Barr recommends an electrical resistivity survey be conducted in order to confirm grounding and

cathodic protection design parameters. The work should be performed in accordance with ASTM

method G57-06 “Standard Test Method for Field Measurement of Soil Resistivity Using the Wenner

Four-Electrode Method” (equivalent to IEEE Std. 81-1983). Testing should be conducted at each

construction site or at a representative number of sites for each soil type and topographic setting.

High soil resistivity and thin soil cover can affect the design of the wind turbine ground grid. The

soil conditions necessary for acceptable grounding are compromised due to the conditions listed in

the preceding paragraphs. Options to address poor soil conditions can include reduced spacing

between grounding conductors and a ground grid with a larger area to reduce the ground resistance.

The reduced spacing can also address issues related to touch and step potentials. The potential for

higher ground potential rise can also require the installation of isolation equipment on copper based

communication circuits, and can result in power conductors with increased insulation resistance.



Collector circuits generally operate at 35 kV (nominal). The National Electrical Code requires a

burial depth of 36” for direct buried circuits. The burial depth can be reduced to 24” when the

circuits are installed in rigid non-metallic conduit, or 6” when installed in intermediate metallic

conduit or rigid steel conduit. San Diego County may also require ‘wrapping’ of metallic conduit for

corrosion resistance. If thinner soil conditions are encountered, cutting channels in the rock or

surface mounted conduit may be options. These electrical system requirements, which are unusual

for most wind projects, can significantly affect the price of the project.

6.2 Soil Thermal Resistivity The best approach is to determine site specific values during the geotechnical investigation phase.

6.3 Recommended Testing When Iberdrola Renewables completes the next phase of geotechnical investigation (Section 8), it is

assumed that the number of tests for the electrical design will be equal to about 10 percent of the

number of turbines:

• Complete in situ soil electrical resistivity tests

• Collect and test soil samples for thermal resistivity

• Test and sample locations should be selected by the electrical designer.



7.0 Civil Design

The construction of access roads to the turbines was reviewed with respect to the subgrade,

availability of construction materials, and the topography of the project site.

There are two types of road construction. One on the western edge of the site where turbines are on

the mountain ridges, and the second in the lower elevations were the turbines will be placed on the

crests of the hills and knobs.

The anticipated method for constructing the lower elevation roads is to clear the vegetation, move

boulders, level and compact the ground. The granular character of the area is expected to be suitable

for the road surface. Areas with very high fines such as dry stream beds may require a layer of

gravel.

The roads climbing the mountains and on the mountain ridges will likely be cut into the side slopes

in most cases. A 4 to 6 inch gravel layer would likely be desirable for vehicle traction and durability.

The roads in this section will be steep with long stretches at 10 %.

Production of gravel on site is the likely source of road building materials. Sand is likely available in

dry stream beds and rock can be blasted. This same process can produce aggregate for the concrete

foundations.



8.0 Recommended Field Investigation

Based on Barr’s experience with similar geological terrains, the site may be suitable for support of a

typical spread footing, and either a rock socket, rock anchor, or P&H type foundation. A preliminary

geotechnical investigation is recommended to gather site data to assist in determining the most

economical turbine foundation type or combination of turbine foundation types. A spread footing is

likely feasible at most if not all locations. However, if there are large areas with very thin soils and

very strong rock, then the cost of excavation followed by supplemental lean concrete with engineered

fill needed to level the bedrock, and crushing rock for backfill over the foundation or importing

backfill may justify use of another foundation type. If a second foundation type is suggested, then

evaluation of the rock properties and construction economics will be needed to determine whether a

rock socket, rock anchor or P&H style foundation is economical.

8.1 Preliminary Geotechnical Site Investigation The goals of a preliminary geotechnical site investigation are to (1) assess the magnitude of site

hazards and (2) aid in determining the most economical style of foundation. This should be done

ahead of the final geotechnical investigation such that time and money are best utilized to minimize

costs associated the final geotechnical investigation. The preliminary geotechnical site investigation

consists of a reduced scope aimed at factors that have the greatest potential to influence the project

schedule and cost. At this site, there does not appear to be any significant geologic hazards, but site

reconnaissance by a qualified geotechnical engineer or engineering geologist could confirm this.

A preliminary geotechnical site investigation may be done in phases:

• Phase 1—Conduct site reconnaissance at all proposed turbine locations. Identify locations

susceptible to short duration and high intensity localized flooding. Evaluate risk of other

possible geological hazards (primarily landslides). Complete test pitting to determine soil

thickness to aid in the foundation feasibility study.

• Phase 2—If indicated by the test pitting and preliminary economic analysis, complete a

geotechnical drilling program to provide rock characteristic data for comparing the relative

feasibilities of the rock anchor, rock socket or P&H foundation designs. Other issues like

soil thermal resistivity testing could also be addressed.

The preliminary geotechnical site investigation scope is dependent upon which foundation design

chosen for the project. Table 4 displays scope and investigation costs for each foundation choice.



8.2 Final Geotechnical Site Investigation The final investigation will need to address the data gaps not addressed by the preliminary

investigation collecting sufficient geotechnical data to complete foundation design(s). Since the

scope of the preliminary investigation is uncertain at this time, as is the final turbine foundation

design(s), the potential scope and cost of the final geotechnical investigation may vary.

Rock socket, rock anchor and P&H type foundation locations are limited by the amount of soil

overlying bedrock, typically chosen as three feet. A spread footing type foundation has no

limitations regarding soil depth, but costs associated excavation and backfill in bedrock will be

higher. With that said, a preliminary estimate of soil thicknesses from the USDA NRCS SSURGO

database across the project site indicated approximately half of the 66 proposed turbine locations

have less than two feet of soil overlying bedrock. This indicates that approximately half of the

proposed turbine locations are suitable for a spread footing and approximately half are suitable for a

rock socket, rock anchor and P&H foundations. The final geotechnical investigation scope and costs

were calculated assuming half of the proposed sites are suitable for spread footing type foundations

and the others are adequate for a rock socket or rock anchor type foundation. Final geotechnical

investigation scope and costs are shown in Table 4.

Table 4Estimated Scope and Cost of Future Phases

Phase I Scope Phase I Cost Phase II Scope Phase II Cost

Spread Footing

Foundation

• Geotechnical drilling program at each proposed turbine location consisting of rock coring to approximately 30 feet below ground surface, including the alternate locations, to collect soil and rock samples for laboratory testing, • Perform laboratory testing • Complete Final Geotechnical Report

$3230 to $4030 $45,000

Rock Socket Foundation


$4570 to $5720 $55,000

P&H Foundation


$4570 to $5720Contact P&H for

Foundation Design Costs

Rock Anchor

Foundation


$6810 to $8510 $65,000*

Estimated Foundation Design

Cost

• Conduct site recon for all proposed locations including structural geology mapping of potential rock socket or rock anchor type foundation locations. • Conduct test pitting at all of proposed locations to determine depth to bedrock and collect bulk samples for resistivity testing and road subgrade testing. • Perform laboratory testing. • Complete Phase I Preliminary Geotechnical Investigation Report.

• Complete a geotechnical drilling program at 4 proposed rock socket (or anchor) turbine locations to approximately 60 feet below ground surface. • Provide rock characteristic data for comparing the relative feasibilities of the rock anchor and the rock socket foundation designs • Perform lab testing for both rock socket and rock anchor foundation designs. • Complete Phase II Preliminary Geotechnical Report.

$51110 to $63890

None

$17970 to $22460

* Rock anchor foundation design will require perfomance testing 2 to 5 percent of the total number of rock anchors costing approximately $20,000 per test

Foundation Type

Preliminary Investigation Scope

Final Investigation ScopeFinal Geotechnical Investigation and Cost Per Turbine



8.3 Limitations The opinion of probable costs provided in this report is made on the basis of Barr’s experience

and qualifications and represents Barr’s best judgment as experienced and qualified professionals

familiar with the project. The cost opinion is based on project-related information available to

Barr at this time and includes a conceptual-level design of the project. The opinion of cost may

change as more information becomes available. In addition, since Barr has no control over the

cost of labor, materials, equipment, or services furnished by others, over the contractor’s methods

of determining prices, or over competitive bidding or market conditions, Barr cannot and does

not guarantee that proposals, bids, or actual costs will not vary from the opinion of probable cost

prepared by Barr. If Iberdrola Renewables wishes greater assurance as to probable cost,

Iberdrola Renewables should wait until further information is available.



References

American Petroleum Institute, May 1996. Cathodic Protection of Underground Petroleum Storage Tanks and Piping Systems, API recommended practice 1632, Third Edition.

American Society for Testing and Materials, November 2007. Designation G 57-06: Standard Test Method for Field Measurement of Soil Resistivity Using the Wenner Four-Electrode Method, ASTM, West Conshohocken, PA.

Institute of Electrical and Electronics Engineers, Inc., (IEEE). 1983. ANSI / IEEE Std 81-1983: Guide for Measuring Earth Resistivity, Ground Impedance, and Earth Surface Potentials of a Ground System. IEEE, New York.

International Code Council Inc., International Building Code, 2006.

Mooney, Harold M. 1980. Handbook of Engineering Geophysics Volume 2: Electrical Resistivity. Bison Instruments, Inc., Minneapolis, pp. 1-5.

Natural Resources Conservation Survey (NRCS). Web Soil Survey, accessed at http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx

Telford, W. M., L.P. Geldart, R.E. Sheriff, and D.A. Keys, 1976, Applied Geophysics: Cambridge University Press, New York, pp. 454-455, 860.

Todd, Victoria, 2004. Preliminary Geologic Map of the El Cahon 30’ x 60’ Quadrangle, Southern California. USGS Open-File Report 2004-1361.

USDA NRCS Web soil survey, http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx accessed 23 October 2009.

Figures

MEXICO

8

8

86

2

80

22

78

76

3

7

188

2

79

22

78

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94

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S a n D i e g oS a n D i e g oC o u n t yC o u n t y

I m p e r i a lI m p e r i a lC o u n t yC o u n t y

San Diego

RamonaRamona Anza-Borrego Desert State ParkAnza-Borrego Desert State Park

Cuyamaca Rancho State ParkCuyamaca Rancho State Park

Lake Morena Co ParkLake Morena Co Park

Salton Sea

Lake Henshaw

Clark Lake

El Capitan Reservoir

Barrett LakeMorena Reservoir

Cuyamaca Reservoir

Sutherland Lake

Loveland Reservoir

6 0 6Miles

Figure 1

SITE LOCATIONTule Wind Project

Iberdrola RenewablesSan Diego Co., CA

10 0 10Kilometers

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Preliminary Turbine Location(10/13/2009 Coord.)

California

Nevada

Utah

Oregon Idaho

Arizona

Mc C

ain Valley Rd

Old M

ine Rd

Bia

12

Crestw

ood Rd

Lost Valley Rd

Thin

g Va

lley

Rd

Canebrake Rd

Manzanita R

d

Ribbonwood Rd

William

Rd

Cross Rd

Black Wood Rd

William

s Rd

McC

ain R

d

BIA Route 12

Manzanita R

d

R9

R8R7

R6

R5

R4

R3

R2

R1

Q2

Q1

P5

P4

P3P2

P1N8

N7

N6

N5

N4

N3

N2

N1

M2

M1L9

L8

L7

L6

L5

L4

L3L2

L1

K9

K8

K7K5

K4

K3

K2

K1J9

J8J6

J5

J4

J3

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J1

G9

G8

G7

G6

G5

G4

G3

G2G1

F6

F5

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F3

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F1

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E8E7E6E5E4E3E2

E1

D9D8

D7

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D4

D3

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D1

C5C4

C3

C2

C1

B7

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R12

R11

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K11

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J10

G17

G16

G15

G14

G13

G12

G11

G10

E12E11

E10

PM-W1

PM-E2

4,000 0 4,000Feet

Figure 2

SITE LAYOUTTule Wind Project


1,200 0 1,200Meters

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Imagery Source: 2009 ESRI, i-cubed, GeoEye

Elsinore fault zone, Coyote Mountain section

Elsinore fault zone, Coyote Mountain section

Elsinore fault zone

Julian section

grMz

Q

gr-m

grMz

Q

Q

QPc

grMz

gr-m sch

Q

Q

Q

sch

gr-m

Q

sch

Q

Tv

sch

P

gr-m

Q

QPc

gr-m

Tv

grMz

QPc

QPc

QPc

m

QPc

QPc

K?

P

Tvgr-m

grMz gr-m

grMz

gr-m

QPc

grMz

K?

QPc

gr-m

Q

Q

K?

Tv

QPc

K?

P

K?

grMz

P

grMz QPc

2.5 0 2.5Miles

Figure 3

BEDROCK GEOLOGYTule Wind Project


3 0 3 6Kilometers

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Quarternary Fault/Fold (USGS)InferredModerately constrainedWell constrained

Prelim. Fault Data (USGS)Moderately ConstrainedWell ConstrainedInferred

Bedrock Geology(K?) Undivided Cretaceous sandstone, shale,and conglomerate; minor nonmarine rocks inPeninsular Ranges(P) Sandstone, siltstone, shale, and conglomerate;in part Pleistocene and Miocene.

(Q) Alluvium, lake, playa, and terrace deposits;unconsolidated and semi-consolidated. Mostlynonmarine, but includes marine deposits nearthe coast.(QPc) Pliocene and/or Pleistocene sandstone,shale, and gravel deposits; in part Miocene.(Tv) Tertiary volcanic flow rocks; minorpyroclastic deposits.(gr-m) Granitic and metamorphic rocks, mostlygneiss and other metamorphic rocks injectedby granitic rocks. Mesozoic to Precambrian.(grMz) Mesozoic granite, quartz monzonite,granodiorite, and quartz diorite(m) Undivided pre-Cenozoic metasedimentaryand metavolcanic rocks of great variety.Mostly slate, quartzite, hornfels, chert, phyllite,mylonite, schist, gneiss, and minor marble.(sch) Schists of various types; mostly Paleozoicor Mesozoic age; some Precambrian; sch,Schists of various types

Imagery Source: 2009 ESRI, i-cubed, GeoEyeData Sources: U.S. Geological Survey, 2006, http//earthquakes.usgs.gov/regional/qfaults/ California Geological Survey

ToE2Tollhouse

LcE2La Posta

LaE2La Posta

LaE2La Posta

SpG2Sheephead

AcGAcid igneous rock land

LaE2La Posta

LdGLa Posta

LcE2La Posta

KcD2Kitchen Creek

LcE2La Posta

CaC2Calpine

ToGTollhouse

ToGTollhouse

ToGTollhouse

LcE2La Posta

BbG2Bancas

HnEHolland

ToE2Tollhouse

ToE2Tollhouse


LcE2La Posta

LcE2La Posta

MvCMottsville


LcF2La Posta

LcE2La Posta

LdELa Posta

ToGTollhouse

CeCCarrizo

SpE2Sheephead

KcCKitchen Creek

MvCMottsville

MvCMottsville

MvCMottsville

MvCMottsville

KcD2Kitchen Creek

MvCMottsville

MvCMottsville

LdGLa Posta

CaC2Calpine


LcE2La Posta

CaC2Calpine

BbGBancas

SvEStony land

LdELa Posta

MvCMottsville

LuLoamy alluvial land

SpE2Sheephead

LcE2La Posta

KcCKitchen Creek

MvDMottsville

MvCMottsville

MvCMottsville

MvDMottsville

MvDMottsville

LcE2La Posta

LdELa Posta

KcCKitchen Creek

CaC2Calpine

HnGHolland

MvDMottsville

MvAMottsville

ToE2Tollhouse

MvCMottsville

LaE3La Posta

MvDMottsville

MvDMottsville

CaCCalpine

LcE2La Posta

RsARositas

MvCMottsville

LcE2La Posta

MvCMottsville

MvCMottsville

LcE2La Posta

LaE3La Posta

CaCCalpine

HmDHolland


KcD2Kitchen Creek

MvCMottsville

KcCKitchen Creek

MvCMottsville

MvCMottsville

MvCMottsville

LcE2La Posta

MvCMottsville

KcCKitchen Creek

MvCMottsville

MvCMottsville

LcE2La Posta

MvCMottsville

MvCMottsville

MvCMottsville


RmRiverwash

MvCMottsville Lu

Loamy alluvial land

BbEBancas

CaBCalpine

RsCRositas

ToE2Tollhouse

HnGHolland

ToE2Tollhouse

MvDMottsville

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ToE2Tollhouse


MvDMottsville

ToE2Tollhouse

MvDMottsville

MvDMottsville

MvDMottsville

MvDMottsville

MvCMottsville

MvCMottsville

MvCMottsville

HmDHolland

MvCMottsville

ToE2Tollhouse


HmDHolland

MvCMottsville


LcE2La Posta


LcE2La Posta

LcE2La Posta

BbEBancas


ToE2Tollhouse

BbEBancas

MvCMottsville


R9

R8R7

R6

R5

R4

R3

R2

R1

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Q1

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P4

P3P2

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N6

N5

N4

N3

N2

N1

M2

M1L9

L8

L7

L6

L5

L4

L3L2L1

K9

K8

K7

K5K4

K3

K2

K1J9

J8J6

J5

J4

J3

J2

J1

G9

G8

G7

G6

G5

G4

G3

G2G1

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F5

F4

F3

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F1

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E1

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D7

D6

D5

D4

D3

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D1

C5C4

C3

C2

C1

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B6

B5

B4

B3

B2

B1

A8

A7

A6

A5

A4

A3

A2

A1

R12R11

R10

L11

L10

K12

K11

J15

J14

J11

J10

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G16

G15

G14

G13

G12

G11

G10

E12E11

E10

PM-W1

PM-E2

4,000 0 4,000Feet

Figure 4

SOIL MAPTule Wind Project


1,200 0 1,200Meters

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Soil Map Unit

Imagery Source: 2009 ESRI, i-cubed, GeoEyeData Source: USDA NRCS SSURGO Database

SM

GW

CL-ML

ML

GW-GM

SM

SM

SM

CL-ML

CL-ML

R9

R8R7

R6

R5

R4

R3

R2

R1

Q2

Q1

P5

P4

P3P2

P1N8

N7

N6

N5

N4

N3

N2

N1

M2

M1L9

L8

L7

L6

L5

L4

L3L2

L1

K9

K8

K7K5

K4

K3

K2

K1J9

J8J6

J5

J4

J3

J2

J1

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G8

G7

G6

G5

G4

G3

G2G1

F6

F5

F4

F3

F2

F1

E9

E8E7E6E5E4E3E2

E1

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D7

D6

D5

D4

D3

D2

D1

C5C4

C3

C2

C1

B7

B6

B5

B4

B3

B2

B1

A8

A7

A6

A5

A4

A3

A2

A1

R12

R11

R10

L11

L10

K12

K11

J15

J14

J13

J11

J10

G17

G16

G15

G14

G13

G12

G11

G10

E12E11

E10

PM-W1

PM-E2

4,000 0 4,000Feet

Figure 5

UNIFIED SOIL CLASSIFICATIONTule Wind Project


1,200 0 1,200Meters

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Unified Soil Classification

Undefined

CL-ML

GW

GW-GM

ML

SM

Imagery Source: 2009 ESRI, i-cubed, GeoEye

ToE2Tollhouse

LcE2La Posta

LaE2La Posta

LaE2La Posta

SpG2Sheephead


LaE2La Posta

LdGLa Posta

LcE2La Posta

KcD2Kitchen Creek

LcE2La Posta

CaC2Calpine

ToGTollhouse

ToGTollhouse

ToGTollhouse

LcE2La Posta

BbG2Bancas

HnEHolland

ToE2Tollhouse

ToE2Tollhouse


LcE2La Posta

LcE2La Posta

MvCMottsville


LcF2La Posta

LcE2La Posta

LdELa Posta

ToGTollhouse

CeCCarrizo

SpE2Sheephead

KcCKitchen Creek

MvCMottsville

MvCMottsville

MvCMottsville

MvCMottsville

KcD2Kitchen Creek

MvCMottsville

MvCMottsville

LdGLa Posta

CaC2Calpine


LcE2La Posta

CaC2Calpine

BbGBancas

SvEStony land

LdELa Posta

MvCMottsville


SpE2Sheephead

LcE2La Posta

KcCKitchen Creek

MvDMottsville

MvCMottsville

MvCMottsville

MvDMottsville

MvDMottsville

LcE2La Posta

LdELa Posta

KcCKitchen Creek

CaC2Calpine

HnGHolland

MvDMottsville

MvAMottsville

ToE2Tollhouse

MvCMottsville

LaE3La Posta

MvDMottsville

MvDMottsville

CaCCalpine

LcE2La Posta

RsARositas

MvCMottsville

LcE2La Posta

MvCMottsville

MvCMottsville

LcE2La Posta

LaE3La Posta

CaCCalpine

HmDHolland


KcD2Kitchen Creek

MvCMottsville

KcCKitchen Creek

MvCMottsville

MvCMottsville

MvCMottsville

LcE2La Posta

MvCMottsville

KcCKitchen Creek

MvCMottsville

MvCMottsville

LcE2La Posta

MvCMottsville

MvCMottsville

MvCMottsville


RmRiverwash

MvCMottsville Lu

Loamy alluvial land

BbEBancas

CaBCalpine

RsCRositas

ToE2Tollhouse

HnGHolland

ToE2Tollhouse

MvDMottsville

SpE2Sheephead

ToE2Tollhouse


MvDMottsville

ToE2Tollhouse

MvDMottsville

MvDMottsville

MvDMottsville

MvDMottsville

MvCMottsville

MvCMottsville

MvCMottsville

HmDHolland

MvCMottsville

ToE2Tollhouse


HmDHolland

MvCMottsville


LcE2La Posta


LcE2La Posta

LcE2La Posta

BbEBancas


ToE2Tollhouse

BbEBancas

MvCMottsville


R9

R8R7

R6

R5

R4

R3

R2

R1

Q2

Q1

P5

P4

P3P2

P1N8

N7

N6

N5

N4

N3

N2

N1

M2

M1L9

L8

L7

L6

L5

L4

L3L2L1

K9

K8

K7

K5K4

K3

K2

K1J9

J8J6

J5

J4

J3

J2

J1

G9

G8

G7

G6

G5

G4

G3

G2G1

F6

F5

F4

F3

F2

F1

E9

E8E7E6E5E4E3E2

E1

D9D8

D7

D6

D5

D4

D3

D2

D1

C5C4

C3

C2

C1

B7

B6

B5

B4

B3

B2

B1

A8

A7

A6

A5

A4

A3

A2

A1

R12R11

R10

L11

L10

K12

K11

J15

J14

J11

J10

G17

G16

G15

G14

G13

G12

G11

G10

E12E11

E10

PM-W1

PM-E2

4,000 0 4,000Feet

Figure 6

DEPTH TO WEATHERED BEDROCK

Tule Wind ProjectIberdrola Renewables

San Diego Co., CA

1,200 0 1,200Meters

Barr Footer: Date: 11/24/2009 11:59:25 AM File: I:\Projects\05\37\007\2009\Maps\Reports\Geotech_Report_Nov09\Fig06 Depth to Weathered Bedrock.mxd User: mbs2


Unspecified/Greater than 150 cm

0 - 50 cm

50 - 100 cm

100 - 150 cm

Imagery Source: 2009 ESRI, i-cubed, GeoEyeData Source: USGS SSURGO Database

Appendix Site Seismic Information

Conterminous 48 States2006 International Building CodeLatitude = 32.83Longitude = -116.37Spectral Response Accelerations Ss and S1Ss and S1 = Mapped Spectral Acceleration ValuesSite Class B - Fa = 1.0 ,Fv = 1.0Data are based on a 0.009999999776482582 deg grid spacing Period Sa (sec) (g) 0.2 1.429 (Ss, Site Class B) 1.0 0.519 (S1, Site Class B)

Conterminous 48 States2006 International Building CodeLatitude = 32.83Longitude = -116.37Spectral Response Accelerations SMs and SM1SMs = Fa x Ss and SM1 = Fv x S1Site Class B - Fa = 1.0 ,Fv = 1.0

Period Sa (sec) (g) 0.2 1.429 (SMs, Site Class B) 1.0 0.519 (SM1, Site Class B)

Conterminous 48 States2006 International Building CodeLatitude = 32.83Longitude = -116.37Design Spectral Response Accelerations SDs and SD1SDs = 2/3 x SMs and SD1 = 2/3 x SM1Site Class B - Fa = 1.0 ,Fv = 1.0

Period Sa (sec) (g) 0.2 0.953 (SDs, Site Class B) 1.0 0.346 (SD1, Site Class B)

Conterminous 48 States2006 International Building CodeLatitude = 32.76Longitude = -116.28Spectral Response Accelerations Ss and S1Ss and S1 = Mapped Spectral Acceleration ValuesSite Class B - Fa = 1.0 ,Fv = 1.0Data are based on a 0.009999999776482582 deg grid spacing Period Sa (sec) (g) 0.2 1.283 (Ss, Site Class B) 1.0 0.450 (S1, Site Class B)

Conterminous 48 States2006 International Building CodeLatitude = 32.76Longitude = -116.28Spectral Response Accelerations SMs and SM1SMs = Fa x Ss and SM1 = Fv x S1Site Class B - Fa = 1.0 ,Fv = 1.0

Period Sa (sec) (g) 0.2 1.283 (SMs, Site Class B) 1.0 0.450 (SM1, Site Class B)

Conterminous 48 States2006 International Building CodeLatitude = 32.76Longitude = -116.28Design Spectral Response Accelerations SDs and SD1SDs = 2/3 x SMs and SD1 = 2/3 x SM1Site Class B - Fa = 1.0 ,Fv = 1.0

Period Sa (sec) (g) 0.2 0.855 (SDs, Site Class B) 1.0 0.300 (SD1, Site Class B)

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Probabilistic Seismic Hazards Mapping Ground Motion Page

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Ground Motions for User Selected Site

Ground motions (10% probability of being exceeded in 50 years) are expressed as a fraction of the acceleration due to gravity (g). Three values of ground motion are shown, peak ground acceleration (Pga), spectral acceleration(Sa) at short (0.2 second) and moderately long (1.0 second) periods. Ground motion values are also modified by the local site soil conditions. Each ground motion value is shown for 3 different site conditions: firm rock (conditions on the boundary between site categories B and C as defined by the building code), soft rock (site category C) and alluvium (site category D).

NEHRP Soil Corrections were used to calculate Soft Rock and Alluvium. Ground Motion values were interpolated from a grid (0.05 degree spacing) of calculated values. Interpolated ground motion may not equal values calculated for a specific site, therefore these values are not intended for design or analysis.

Longitude -116.32 Latitude 32.8

Ground Motion Firm Rock Soft Rock AlluviumPga 0.327 0.342 0.374 Sa 0.2 sec 0.784 0.826 0.901 Sa 1.0 sec 0.282 0.353 0.437

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Last edited on June 12, 2008

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